The overall goal of the proposed research project is to test for ethnic differences in the internal and external validity of DSM-IV ADHD in an African American (AA) sample. In order to test for ethnic differences in the internal validity of DSM-IV ADHD, this study will examine symptom dimensions and DSM-IV subtypes in two community samples of African American (AA) and Caucasian American (CA) subjects, divided by ethnic group and gender within each group. In order to test for ethnic differences in the external validity of DSM-IV ADHD, the current study will examine whether important clinical correlates of ADHD, namely functional impairment, academic achievement, and comorbidities with other psychiatric disorders, vary by ethnic group or gender. In addition, this study will examine whether there are ethnic or gender group differences in the neuropsychological profiles of children with ADHD. We will compare the performance of participants by group and by gender within group on measures of behavioral inhibition, sustained attention and vigilance, working memory, processing speed, delay aversion, and affective decision making to determine whether the same deficits exist, in the same proportions, in an AA sample as in a CA sample. [unreadable] [unreadable] [unreadable]